The present invention relates to a polymeric composite material and a method for producing the same, especially to a kneading method.
In a conventional method for dispersing a clay layer in a thermoplastic resin, an organophilic clay and the thermoplastic resin are melt-kneaded in a twin-screw extruder. One of such kneading methods is disclosed in Japanese Laid-Open Patent Publication No. 9-217012. In this method, a kneading condition is set based on a mixing coefficient Mix and a shear coefficient F.
However, such a kneading condition involves difficulties in exerting a sufficient shear stress and a sufficient shear energy to an organophilic clay and a thermoplastic resin, resulting in insufficient micro-dispersion of a clay layer. Thus, when the kneading was performed under a conventional condition described above, the clay was aggregated into five layers in a thermoplastic resin. Accordingly, the gas barrier performance was poorer than that produced by a polymerization method such as that disclosed in Japanese Laid-Open Patent Publication No.62-74957.
(Objective of the Invention)
An objective of the present invention is: to provide a polymeric composite material capable of micro-dispersing an organophilic clay in a thermoplastic resin and a method for producing the same.
(Constitution of the Invention)
The present invention is a method for producing a polymeric composite material comprising:
melt-kneading an organophilic clay and a polymer in a condition that the average value (Pxe2x80x2ave) and the maximum value (Pxe2x80x2max) of a reduced pressure on resin at one or more loading regions of a kneaded material comprising the organophilic clay and the polymer in a kneader are within the ranges shown below and that a total shear strain (A) and/or a total shear energy per unit volume (E) in all loading regions of the kneaded material are within the ranges of
Pxe2x80x2avexe2x89xa75xc3x97104(Pa),
Pxe2x80x2maxxe2x89xa71xc3x97105(Pa),
105xe2x89xa6Axe2x89xa6107, and
1010(Pa)xe2x89xa6Exe2x89xa61014(Pa).
(Effect of the Invention)
In a method for producing a polymeric composite material according to the present invention, the average value (Pxe2x80x2ave) of a reduced pressure on resin Pxe2x80x2 at one or more loading regions of a kneaded material in a kneader is 5xc3x97104 (Pa) or higher, and the maximum value (Pxe2x80x2max) is 1xc3x97105 (Pa) or higher. With such values, there is no void in the loading region, resulting in no slip of a polymer upon being subjected to a shear stress, which enables an efficient application of a shear stress and/or a shear energy to the kneaded polymer.
Also in the inventive production method, a total shear strain (A) and/or a shear energy per unit volume (E) in all loading regions of the kneaded material are within the ranges: 105xe2x89xa6Axe2x89xa6107, 1010(Pa)xe2x89xa6Exe2x89xa61014(Pa). With such values, an organophilic clay can uniformly be micro-dispersed without degrading any properties of a polymer.
(Effect of the Invention)
According to the method of the present invention, a sufficient shear stress can be applied to an organophilic clay and a polymer, thereby achieving a sufficient micro-dispersion of the organophilic clay layers throughout a polymer.
Also by using a polymeric composite material obtained according to the present invention, an article of the polymeric composite material which is excellent in its properties such as gas barrier performance, tensile strength and elongation can be obtained.